textproduct: Rapid City

KEY MESSAGES

- Hot weather will continue through the weekend with daily chances for active thunderstorms as ridge-riders rotate through the northern Plains.

UPDATE

Issued at 948 PM MDT Mon Jul 27 2026

KUDX radar shows lingering showers across central to southwestern South Dakota. Obs show temps have dropped into the 70s across the CWA...and 60s over the Black Hills. CAMs are suggesting isolated showers will be possible the rest of the night, so will leave some minor pops over western SD south of I-90. No significant changes needed with the forecast tomorrow. Upper ridging continues across the region with highs tomorrow in the 90s. There is perhaps a weak shortwave that comes through late in the day, with storms developing in NE WY and the Black Hills, then moving into western SD where higher instability will be in place. Shear will generally be weak, but can't rule out a few strong storms, especially ones with gusty winds. Storm coverage tomorrow will definitely be less than today.

DISCUSSION

(This Afternoon Through Sunday) Issued at 1048 AM MDT Mon Jul 27 2026

16z surface analysis had a low over northeastern WY with a couple of troughs; one south into CO and another east into eastern SD. Sustained east/southeast flow over western SD bringing increasing moisture to the area. Water vapour loop has upper ridge centered over NM with ridge axis into the northern Plains. Shortwave evident over northwest WY, ready to overtop the ridge and cross the CWA during peak insolation this afternoon/evening. That will be the main short term concern.

This afternoon/tonight, 1-2KJ/kg SBCAPE develops along the aforementioned boundaries with similar amounts of DCAPE. Effective shear forecast to be 30-45kts as shortwave crosses. CAMs show convective initiation by 20z, focused on the higher terrain initially and then the surface boundaries as SBCIN erodes. Clusters of storms will move east, potentially with congealing cold pools, increasing the damaging wind threat. CAMs show a couple clusters of enhanced wind gusts. Thunderstorms end overnight. Temperatures will be near guidance, but below heat headline criteria.

Tuesday looks less active right now given shortwave ridging and lack of a distinct shortwave moving through the area, but would still expect some convection tied to the terrain. Wednesday, ensemble guidance shows another distinct wave moving across the area during peak heating resulting in an elevated risk of severe weather. Temperatures remain hot, but below heat headlines criteria.

The rest of the forecast will be dominated by the upper ridge over the central CONUS and hot weather. There will be waves kicking off a few storms from time-to-time. If you believe the long term ensemble guidance, someone of a cooldown may develop next week, but confidence low.

AVIATION

(For the 06Z TAFS Through 06Z Tuesday Night) Issued At 1056 PM MDT Mon Jul 27 2026

VFR conditions are generally expected throughout the current forecast period. CAMs still supporting isolated thunderstorm development after about 19z/1pm Tuesday over northeast Wyoming and the Black Hills, perhaps spilling/drifting into adjacent South Dakota plains later in the afternoon. Storms may produce brief drops to MVFR and gusty/erratic outflow winds. Overall confidence in location/timing is still a bit marginal to introduce any PROB30s at the TAF terminals, so will continue to hold with a dry forecast for now.

FIRE WEATHER

Issued At 1048 AM MDT Mon Jul 27 2026

Elevated fire weather conditions are expected much of this week due to hot temperatures as well as minimum relative humidity in the teens and 20s at times. The joint probability of MinRH <15% and winds >25mph low at this point. The cores of thunderstorms that occur this week should contain wetting rain, but lightning strikes outside of the cores as well as strong, erratic winds may create opportunities for new fires.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.